The assignee of the present invention manufactures and deploys spacecraft for, inter alia, communications and broadcast services from geostationary orbit. During launch, such spacecraft are enclosed within a launch vehicle payload fairing that experiences depressurization to a near vacuum condition from an initial pressure of nominally one atmosphere (approximately 14.7 PSIA) within a time period of about two minutes. To safely accommodate this pressure change, the spacecraft design must include provisions for safely venting of air from interior volumes of the spacecraft and spacecraft components into the launch vehicle payload fairing.
Large structural components of a spacecraft include spacecraft equipment and solar array panels and structural panels that may be in the range of 60 to 80 square feet surface area. Referring to FIG. 1, an exploded isometric view of a typical panel 100 is illustrated. Panel 100 includes a honeycomb core 110 sandwiched between panel faceskins 120. The panel face skins 120 may be adhered to a honeycomb core 110 by epoxy adhesive or other adhesive bond, for example. Referring now to views A-A and B-B of FIG. 1 each cell in the honeycomb core is intended to be vented (by slitting or perforating, for example) to permitted air to escape during launch as the spacecraft leaves the earth's surface and experiences a depressurization from approximately one atmosphere of pressure to the vacuum of space.
In practice, however, it has been found that some cells of an as-fabricated honeycomb panel may exhibit manufacturing defects as a result of which the defective cells fail to comply with the design intent of providing safe venting means. Such manufacturing flaws are difficult to completely prevent and may be difficult to detect by conventional inspection or nondestructive test techniques. A consequence of such undetected flaws can include explosive rupture of the panel, and resulting damage to spacecraft functional systems.
As a result, an improved approach to testing the venting capacity of such structures is desirable.